Emission gas recycling equipment having butterfly valve

Abstract

Emission gas recycling equipment includes a passage for recycling a part of an emission gas and a control valve for controlling an amount of the part of the emission gas. The control valve includes: a housing having a pipe portion; a butterfly valve accommodated in the pipe portion rotatable in a first direction and a second direction; a seal ring for sealing a clearance; and valve open / close operation means for stopping the butterfly valve at the valve full close position after the valve open / close operation means operates the butterfly valve to open and to close equal to or more than one cycle across the valve full close position at the time when the engine stops or after the engine stops.

Description

CROSS REFERENCE TO RELATED APPLICATION[0001]This application is based on Japanese Patent Application No. 2004-42588 filed on Feb. 19, 2004, the disclosure of which is incorporated herein by reference.[0002]1. Field of the Invention[0003]The present invention relates to emission gas recycling equipment having a butterfly valve.[0004]2. Background of the Invention[0005]Emission gas recycling equipment according to a related art is well-known. In the equipment, an emission gas recycling gas (i.e., EGR gas) as a part of the emission gas flowing through an exhaust pipe of an engine is mixed into an intake air flowing through an intake pipe so that the maximum combustion temperature is reduced. Thus, toxic substance (e.g., a nitrogen oxide) included in the emission gas is reduced. However, when the emission gas is recycled, engine power is reduced, and driving performance of the engine is reduced. Therefore, it is required to control an amount of the recycling emission gas (i.e., an EGR a...

AI Technical Summary

Benefits of technology

The present invention provides an emission gas recycling equipment with a butterfly valve for controlling the amount of recycled emission gas. The butterfly valve has a seal ring to seal the clearance between the inner wall of the pipe portion and the outer wall of the butterfly valve when the butterfly valve is positioned at the valve full close position. The seal ring is accommodated in the outer diameter of the butterfly valve. The butterfly valve is rotatable in a range between the valve full open position and a predetermined position. The valve open / close operation means stops the butterfly valve at the valve full close position when the engine stops or after the engine stops. The butterfly valve with the seal ring prevents deposition of fine particles and ensures smooth operation. The recycling emission gas amount control valve can optimize the recycling emission gas amount to correspond to the driving condition of the engine.

Problems solved by technology

However, when the emission gas is recycled, engine power is reduced, and driving performance of the engine is reduced.

If the deposit of the fine particle is deposited to bridge between the inner diameter surface of the passage and the outer diameter periphery of the butterfly valve, the butterfly valve is not operated smoothly by an actuator such as the torque motor.

Accordingly, the butterfly valve is not operated smoothly by the actuator such as the torque motor after the engine starts.

Thus, a possibility of a problem exists, the problem being that the recycling emission gas amount (i.e., EGR amount) cannot be adjusted to correspond to the driving condition of the engine.

However, the recycling emission gas amount cannot be precisely adjusted to correspond to the driving condition of the engine, since the butterfly valve is not sealed.

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